Kim Jong Nam arriving at an airport in Beijing in a photo taken by the Kyodo news agency.
Thomson Reuters
KUALA LUMPUR, Malaysia — Four men suspected of killing the North Korean leader's half-brother at a Malaysian airport changed their clothes and appearance to escape detection, a police witness said on Thursday.

The four, who are still at large, are charged together with two women — Indonesian Siti Aisyah and Doan Thi Huong from Vietnam — with killing Kim Jong Nam at Kuala Lumpur airport's budget terminal on February 13.

Prosecutors in the Malaysian court say Siti Aisyah and Huong conspired with the men to murder Kim by smearing his face with liquid VX, a chemical poison banned by the United Nations.

Defense lawyers have argued that the women did not know they were handling poison and thought they were involved in a prank for a reality-TV show.

The men had been formerly identified only as Mr. Chang, Mr. Y, James, and Hanamori, also known as "Grandpa" or "Uncle," which a police witness has said were assumed names.

The men changed clothes before they were seen leaving the airport, the police investigator Wan Azirul Nizam Che Wan Aziz told the court.

"They were trying to confuse (observers)," Wan Azirul said, describing closed-circuit television recordings made on the day of the killing.

More than 40 CCTV video clips of the men's movements at the airport were screened in the darkened courtroom.

They showed Mr. Chang and Mr. Y heading to different bathrooms in the airport before emerging in different clothes, shortly after the attack on Kim Jong Nam.

Mr. Chang, who had earlier been seen wearing a goatee, also came out of the bathroom clean-shaven.

"All of the suspects at large, even though they changed clothes, did not change their shoes," added Wan Azirul, who said the shoes were among the features enabling identification of the suspects, besides their body types and movements.

A hazmat team at the KLIA2 airport in Sepang, Malaysia, on February 26.
REUTERS/Edgar Su

Other videos showed Mr. Chang and Mr. Y meeting separately with a man, identified as Hanamori, at a restaurant near the airport's check-in counters, prior to the attack.

Hanamori was seen arriving at the restaurant with a fourth man, who Wan Azirul said was "suspected to be James."

Mr. Chang later met alone with Siti Aisyah at the restaurant, while Mr. Y was seen walking past the restaurant with Huong.

It is unclear whether the four suspects at large were the same four North Koreans authorities described as having left Kuala Lumpur for Pyongyang on the day of the killing.

An image from CCTV footage of a man purported to be Kim Jong Nam (circled in red) seemingly talking to airport staff members at Kuala Lumpur International Airport in Malaysia on February 13 after being accosted by a woman in a white shirt.
FUJITV/via Reuters TV

An Interpol alert has been issued for the four who left, identified as North Koreans Ri Ji Hyon, Hong Song Hac, O Jong Gil, and Ri Jae Nam.

US and South Korean officials have said agents of Kim Jong Un's regime masterminded the killing.